Ordinary 2D display system mainly comprises a display device and a control means connected to the display device (e.g. the host of a computer, cell phone, etc.). The drive means in the display device (e.g. the graphic card) receives video signals from the control means, and control image-displaying on the display screen of the display device according to the video signals. A standard video transmission protocol is used between the control means and the drive means in the display device. In the video signals based on a standard video transmission protocol from the control means, the vertical blank of each frame period constitutes a pretty short portion of each frame period, e.g. the vertical blank of each frame period constitutes 1%-2% of each frame period in the case of video signals based on a standard DVI (Digital Video Interface) protocol.
Like the 2D display system, a 3D display system also comprises a display device and a control means connected to the display device. And the drive means in the display device (e.g. the graphic card) receives video signals from the control means, and control image-displaying on the display screen of the display device according to the video signals. The difference is that images for left eye are different from the images for right eye in the principle of the 3D display system, what left eye sees are images corresponding to the left eye, and what right eye sees are images corresponding to the right eye, so that the 3D display system also comprise 3D glasses which are controlled. Specifically, two sets of images, one set for left eye and one set for right eye are actually displayed on the display device. Each of frame period in the video signals corresponds to image for left eye and image for right eye in turn. Correspondingly, images for left eye and images for right eye appear on the display screen in turn. When showing one frame of image for one eye, the other eye which is not supposed to see that frame of image is blocked by controlling the 3D glasses.
In addition, each frame of image is seen by one eye, but during the scan stage of that frame image (the transmission stage of the image), the image should not be seen by the eye. Only in the stage when the scan of the image is completed (the vertical blank stage) should light be passed (i.e. light are allowed to enter the eye). And the level of feeling about the frame of image that the eye experiences is the integral of brightness of the image and time of feeling. So that in the present art of 3D display, both lenses of the 3D glasses are blocked via control (in general the lenses are turned to black by switching on current). The vertical blank of each frame of video signals constitutes a longer portion of each frame period, in order to ensure that the viewers see the video images with enough brightness and clarity. However, the duration of the vertical blank of each frame of video signals cannot be extended without limitation as the phenomenon of ghosting has to be avoid. Furthermore, the backlight of the backlight means in the 3D display device is continuously in a state of being turned on.
For example, when the video signals are based on a DVI protocol, the vertical blank constitutes at most 32% of each frame of video signals, otherwise there will be a problem of ghosting in the present art, as shown in FIG. 1. Also, corresponding to each frame of video signals, only one of the lenses of the 3D glasses is pervious to light during the vertical blank of that frame of video signal. In FIG. 1, in the coordinate of video signals, ‘1’ represents that the frame of video signals is being transmitted while ‘0’ represents that the transmission of the frame of video signals is completed, i.e. the vertical blank. In the coordinate of the state of lenses, ‘0’ represents that both of the lenses are blocked, ‘1’ represents that the left lens is pervious to light and ‘−1’ represents that the right lens is pervious to light. The backlight of the backlight means is continuously in a state of being turned on.
Thus, only a portion of the brightness (corresponding to the vertical blank) provided by the backlight means enters the eyes of the viewer(s). Besides, longer vertical blanks constitute a larger portion of bandwidth of digital link of the video signals. And the longer vertical blanks also demand anon-standard video transmission protocol between the control means and the drive means. So that the ordinary drive means has to be altered (i.e. a non-standard drive means is used). However, the non-standard drive means is non beneficial for further update of the product.
Therefore, there is a need of providing a 3D display device, a 3D display system and a method for displaying 3D image to solve the above problems.